Page 1 of 1

Chamber fan. Do I really need it for propane meter injection

Posted: Tue Jan 15, 2013 8:51 pm
by Ziptietech
Well I finished my canon and I forgot to put in a chamber fan. Well I'm not able to take it apart now and I can't get in the chaner because I used a 3in to a 1 1/2 reducer to a ball valve.

I can't fire it until I go on vacation b
So I can't check of it works

Do I really need the fan?? Or will it work without it.

Posted: Tue Jan 15, 2013 9:32 pm
by mark.f
It will work without it. However, power will be reduced a by a not-insignificant amount.

You've now learned the lesson it took forever for JSR to learn... make your projects serviceable. :p

Good luck with the project.

Posted: Tue Jan 15, 2013 9:39 pm
by Ziptietech
Lol thanks that will calm my nerves a little lol.

Yea I didn't think about the fan when I was gluing it haha.

Thanks for the help

Posted: Tue Jan 15, 2013 10:19 pm
by mark.f
You could throw some airsoft bb's or pennies into the chamber for fuel mixing. :roll: I've done it before with pennies on a small launcher I made.

Posted: Tue Jan 15, 2013 10:33 pm
by Ziptietech
Well I made my canon have a tire valve for propane injection. And I was wondering if I can pumpe extra air in too to Mix the air. But if it isn't too much of a deal ill just shot it without a fan. If it doesn't work ill cut the camber off and put in a fan and add a coupler with a screw on cap in the rear

Posted: Thu Jan 17, 2013 7:22 am
by anarchy08
I had a propane cannon running 100mm X400 combustion chamber and can tell you the difference between operating a chamber fan with and without is HUGE! even from dry firing you could tell that you were getting a more complete mix- the death of that cannon actually came from the fuel air becoming too efficient and self destructing in operating. fired off a good 100 odd golf balls before it stress failed

Posted: Thu Jan 17, 2013 7:55 am
by ramses
Ziptietech wrote:Well I made my canon have a tire valve for propane injection. And I was wondering if I can pumpe extra air in too to Mix the air. But if it isn't too much of a deal ill just shot it without a fan. If it doesn't work ill cut the camber off and put in a fan and add a coupler with a screw on cap in the rear
In either case, adding air will throw the fuel mixture off. If you let the air escape, you just need to aim high. If you don't allow the air to escape, you have built a hybrid, which will require a burst disk or some other valve (and probably shouldn't be made out of PVC)

They do sell some very small PC fans that could probably fit through the 1/2" ball valve, but making connections and securely mounting it would be a pain.

Posted: Thu Jan 17, 2013 3:23 pm
by jimmy101
A fan doesn't make that much difference IF the fuel is well mixed. The fan just helps to mix the fuel faster. If you are patient the gun'll work fine. After fueling wait a couple minutes before firing to give the fuel time to properly mix with the air in the chamber.

Posted: Thu Jan 24, 2013 12:19 am
by Squerl101
Yeah, the fan is just there to increase efficiency of the fuel, so that it fills every cubic centimeter of your combustion chamber for maximum power. It will definitely work without it though, I don't have one, and I get a pretty powerful punch when I hit the igniter.

Posted: Thu Jan 24, 2013 12:44 am
by jackssmirkingrevenge
[img]http://profile.ak.fbcdn.net/hprofile-ak-ash3/174583_308788222491481_250794691_q.jpg[/img] wrote:You've now learned the lesson it took forever for JSR to learn... make your projects serviceable. :p
I had missed this :D